Not Applicable
1. Field of the Invention
The present invention relates to equipment for dispensing a carbonated beverage into an open container from which the beverage will be consumed; and more particularly to such equipment in which the dispensing occurs in a manner that minimizes foaming of the beverage.
2. Description of the Related Art
It is common for carbonated beverages, such as soda and beer, to be supplied in a sealed canister or keg which then is connected to a tap at an establishment, such as one that serves food. As used herein the term xe2x80x9cestablishmentxe2x80x9d refers to a business or a residence. Pressurized gas, such as carbon dioxide, is injected into the keg to force the liquid beverage through an outlet tube to the tap from which it is dispensed into various sizes Of cups, mugs and pitchers.
The carbonated beverage usually foams upon entering the serving container. As a consequence, personnel operating the tap typically fill the serving container until the level of foam reaches the brim and then wait for the foam to settle before adding additional beverage. In some instances several iterations of this process are required before the container is filled with liquid to the proper serving level. Such xe2x80x9ctopping offxe2x80x9d necessitated by the foaming of the beverage prolongs the dispensing operation and impedes the ability to fully automate carbonated beverage dispensing.
Automated dispensing is particularly useful in large volume carbonated beverage operations, such as sports arenas and stadiums, where it is desirable to fill each container to the full serving level as fast as possible with minimal waste.
U.S. Pat. No. 5,603,363 describes a dispensing system that satisfies that desire. The carbonated beverage is fed into an elevated tank that is open to the atmosphere so that the beverage stored therein is at atmospheric pressure at all times. A spout is located beneath the tank and has a valve through which the beverage flows into a serving container. Selective operation of the valve and movement of the serving container enable rapid dispensing with minimal foaming. A drawback of this system is that the tank is open to the atmosphere. Thus the beverage tends to degas upon prolonged storage in the tank. In addition, there is a concern that bacteria and other substances may enter the open tank and contaminate the beverage therein, especially between hours of operation of the beveratte establishment.
Alternative systems, such as described in U.S. Pat. No. 3,881,636, employs a closed tank with a vent tube at the top of the tank that provides a restricted passage to the atmosphere. The beverage is fed to the tank under the same pressure as in the keg and is maintained substantially at that elevated pressure until a spout is opened to fill a glass. At that time the tank pressure is reduced to the atmospheric level before the valve on the spout is opened. Upon completion of the dispensing operation the tank is brought back to the keg pressure. In a high volume dispensing establishment, this latter type of dispensing system has the disadvantage that time is lost while the reservoir is brought down to atmospheric pressure before the spout is opened. A further delay results from having to raise the tank to the keg pressure in order replenish the beverage in the tank. Thus it is desirable to increase the speed of dispensing further.
A method for dispensing a carbonated beverage conveys the beverage from a source into a closed reservoir at first pressure level that is greater than atmospheric pressure. In the case of beer, this first pressure typically is the internal pressure of the beer keg as shipped from the brewery, which pressure is known as the xe2x80x9crack pressure.xe2x80x9d The carbonated beverage then is dispensed from the reservoir into an open container.
While being held in the reservoir, the carbonated beverage is maintained at a second pressure level that is less than the first pressure level and substantially greater than atmospheric pressure. This second pressure level is referred to as the xe2x80x9cholding pressure.xe2x80x9d Preferably the second pressure level is at least one psi, and five psi has been found particularly desirable for holding beer at reduced temperatures to minimize degassing. When it is desired to dispense the carbonated beverage into a serving container, the reservoir pressure is reduced to substantially atmospheric pressure. With the reservoir at substantially atmospheric pressure, the carbonated beverage flows into the container with minimal foaming as the beverage is exposed to a relatively small pressure differential.
Another aspect of the dispensing system. relates to opening a valve through which the carbonated beverage flows from the reservoir into the serving container. The valve is opened while the fluid inlets to the reservoir are closed, thereby preventing any additional beverage from entering the reservoir. With the inlets closed, the weight of the carbonated beverage in the spout causes the pressure in the reservoir to decrease below atmospheric pressure, thereby minimizing the flow of beverage into the container as the valve opens. After that valve has opened to a point at which the risk of foaming is negligible, a fluid, such as carbon dioxide for example, is introduced to raise the pressure in the reservoir to substantially the atmospheric pressure or greater. It has been found that increasing the reservoir pressure after the valve opens can improve the dispensing rate or enhance the presentation of the beverage being poured. At the end of the dispensing operation, pressure in the reservoir is allowed to decrease below atmospheric pressure to reduce flow of the carbonated beverage from the reservoir before the valve is closed.
In the preferred operation of the dispensing system, the pressure of the reservoir is raised to the first pressure level during prolonged periods of inactivity, such as when the food service establishment is closed. That higher pressure level enables the carbonated beverage to be stored for such a prolonged time without degassing. The reservoir pressure then is reduced to the second pressure level upon commencement of another dispensing operation.